Berlin and Sydney. Real transactions on the Arbitrum test network, through the Exergy contracts. Each one can be opened and checked.
Prices are illustrative: Jack's grid sells at 35 cents per kWh, Bob's grid buys surplus at 5 cents, and the note changed hands at 25 cents per kWh it holds. The deal is 10 kWh.
Each compared it with his own alternative and came out ahead. When a deal pays for both sides, it happens. When it happens for money, the note has a price.
This case tests the central claim of Exergy at the hardest moment: someone has no energy of his own and no neighbour who can spare any. The note still works: inside a community it buys energy over the wire, and between communities it is sold for money. The buyer takes a note only when a kilowatt-hour through it costs less than one from his socket. And people accept it because behind it stands a share of all the energy in the network's batteries: that energy really exists, just not necessarily next door.
His battery is empty. His neighbours' batteries are empty too, so nobody here can take his notes for energy. He does hold notes, earned earlier when his battery was charging. And he knows that behind them stands a share of the whole network's energy, now sitting in batteries wherever the sun is shining. So he is sure: his notes will be bought by someone whose own battery is empty or short, to pay a neighbour for power with them. He needs money to pay his power bill.
Evening. His workshop has eaten both his battery and all his notes. His grid sells energy at a high price. His neighbour Bob has energy, and in their community, as across the whole Exergy network, members give each other energy for notes. So Jack needs a note, and one that costs less than a kilowatt-hour from his socket.
Battery full since noon, and nowhere to put the surplus: the grid pays pennies for it. Bob is Jack's neighbour; they are in the same community, joined by its wire. A note suits him better than cash: with it he gets energy himself when he is the empty one, or sells it anywhere in the network.
There is no wire between Berlin and Sydney. Hans is empty, Jack is empty, and value still crossed: Hans's notes became money from Sydney, and Jack got his energy from Bob over his own community's wire. What crossed the border was not energy but its value. That is the hardest case. Bob's noon is the everyday one: a surplus the local grid would pay pennies for went to his neighbour for more, and the notes to settle it came from the other side of the planet.
Sydney is 9 hours ahead of Berlin: noon in Sydney is 3 a.m. in Berlin, and 7 p.m. in Sydney is 10 a.m. in Berlin.
Hans is in the Berlin community; Jack and Bob are in the Sydney one. Both communities take part in Exergy, and their members settle energy with each other in notes. It pays everyone: a note gets you energy from a neighbour when you have none, and money anywhere in the network when money is what you need. Energy for a note changes hands only inside a community, over its wire. The note itself can go anywhere.
When Hans's battery was charging, the energy was measured and notes were issued against it. His community credited him his share: 12 notes. Later the battery ran down, and the notes stayed.
Bob's battery went from 9.45 to 13.5 kWh: it is full, 4.05 kWh added. The report is signed by the device and by the community's system; the contract checked both signatures and issued notes against the new energy. The network's stock grew, and the number on every note went up.
In Berlin, Hans is empty, his neighbours are empty, and the power bill is due. In Sydney, Jack is empty and out of notes, and Bob has energy. Jack pays Hans money, and Hans sends him notes worth 10 kWh across the border. On the test network, test ether stands in for money; in real life it is euros or dollars.
Hans pays his bill with that money, not out of his own pocket. His problem is solved.
The exchange runs at the protocol rate: exactly as many notes as hold 10 kWh at the moment of the deal, and nobody haggles over it. The energy flows over the community wire. Not one electron crossed a border. Hans sent Jack slightly more, 11.46: the difference covered a small protocol fee, and Jack has 0.04 left.
Jack got energy cheaper than from his grid. Bob sold his surplus for more than the grid would give.
Bob's battery held 13.5 kWh. He gave Jack 10, the battery caught a little sun, and 3.6 kWh is left. Jack used those 10 kWh, and they left the stock of the whole network: it was 125.55 kWh, now 115.69. The number of notes is the same; nobody burns them. So every note in the network got lighter: from 0.8777 kWh per note to 0.8082, minus 0.07 kWh on each one. Consumption shows up in the number.
This is the state on 7 Oct 2026, after step 5. On 11 Oct Bob's battery sent one more discharge report, and the number became 0.8016. The live number is always on the dashboard.
Along the bottom are the step numbers; up the side, kWh per note (the axis is cropped so the change is visible). The number is below one because part of the energy that notes were once issued against has since been used, while the notes remain. The drop at step 5 is large because the demo network is small: 10 kWh is 8% of its stock. In a large network one such trade barely shows. When batteries charge again, the number goes back up, as in step 2.
There are many sellers and many buyers in the network, and they switch sides from day to day. A seller lowers the price until it is worth it for a buyer, and will sell even for less than his bill: beyond his perimeter he would otherwise get nothing. A buyer whose battery is empty takes the note as soon as it is cheaper than power from the grid, and pays a neighbour with it for energy. Any price between zero and the grid leaves both better off, so deals do not wait for a lucky match. The price is set by their need, not by us.
That same need is the floor. When the price falls to where the energy behind a note is cheaper than the grid, members buy it up for energy. Above the floor, capital comes in for the kilowatt-hours that each note gains over time.
For decades clean energy has lived on tariffs and subsidies. Now its stored energy has liquidity: a means of settlement backed by measured energy, which cannot be printed out of thin air and sells at a market price anywhere in the network. A kilowatt-hour sitting in a battery has stopped being dead weight. It has become liquid. Each new community makes the network stronger for everyone: the more continents, the surer every note is to find a buyer. If your community stores energy, write to us, and we'll help you connect.
keyenergy.io · info@keyenergy.io · linkedin.com/in/magkey